Low Impact Rnd 2 - Not letting me reschedule

Hi all -

I'm trying to r/s a workout as part of a program - and I'm getting the following message:

You have scheduled another instance of FB Low Impact - Round 2 in this time frame.

I'm confuse as to the reason I can't move the dates - this started yesterday, but I thought maybe it was my phone. It also doesn't work on my computer. Any suggestions or is anyone else experiencing this?